* Support overwrite tag

* Fix test case

* Fix support rabbitmq plugin

* fix Unit test rename sw3 to sw6

* Update pom.xml

* fix adjust rabbitmq Unit test

* fix add rabbitmq component in docker component-libraries.yml

* Update RabbitMQProducerInterceptor.java

* Update RabbitMQProducerInterceptor.java

* Move oal tool back into main repo, and fix compile issue.

* Fix two bugs.

* Remove all generated codes.

* Make all oal generated codes out of source control.

* Make mvn compile and package work.

* Fix test cases.

* Make compile right and provide new documents.

* Remove an unnecessary tokens file.

2. Zookeeper implementation of the cluster module using name space to support using same zookeeper cluster by different OAP clusters.

add system env for trace ignore plugin

Remove unused Debug Switches

* Remove the hard codes about DispatcherManager.

* Add comments.

* Fix the alarm being started too many times.

* Remove unnecessary interface.

* Fix wrong status changed

* Service inventory mapping  doesn't update right.

* Remove codes.

* Update submodule skywalking-ui

* Update submodule ui

* Update submodule skywalking-ui

* Fix #1925 Add namespace to service name

* Support alarm in service instance and endpoint.

* Fix alarm default settings and document.

* Fix wrong default setting

* Make service instance and endpoint scopes available in alarm core.

* Fix alarm bug.

Print exception stack into console or log files because of I found some NPE message in the log files. But I don't known where are they from without exception stack. (#1986)

* Update document and user wall.

* Change format.

* user wall updated.

* Fix typo

* Correct namespace description

* Support sampling trace at server side and keep metric right.

* Add a trace sampling document

* Fix wrong default value.

* Fix document issue.

* Fix assemble issue.

* Fix wrong settings and doc.